The present invention relates to the area of explosive materials and more specifically to the stabilization of explosives which are normally susceptible to thermal initiation of catastrophic decomposition with large associated damage.
Heat has present hazards for explosives since they have been known and used. In combat, ammunition is considered vulnerable and, consequently, measures are taken to protect it from incendiaries, fuel fires and other threats. In noncombat situaitons, accidental ignitions occur through excessive heating of energetic materials in their manufacture, transport or storage. An example of destructive self heating is the explosion of 7 million pounds of fertilizer grade ammonium nitrate at Texas City, Tex. with the resultant fatalities of over 560 persons. In that catastrophe, two separate shiploads of the ammonium nitrate exploded in the harbor after self heating to the ignition temperature.
Common explosives used by the military are 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX); octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,2-bis[(nitroxy)methyl]-1,3 -propanediol dinitrate (PETN) in combination with inert binders. Since heat accelerates chemical reaction, it would be beneficial to stabilize these explosive materials to prevent thermal initiation of catastrophic decomposition and yet allow them to initiate and perform when exposed to a fully developed detonation wave form a booster explosive.
Attempts have been made to prevent undesirable thermal initiations in propellants by the use of additives. These approaches have not been reported for explosives. For example, L. H. Caveny et al. Ballistic Research Laboratory, Contract Report No. 278, entitled. "Evaluation of additives to reduce Solid Propellant Flammability in Ambient Air," (December 1975) incorporated chemical additives in composite and high energy propellants. They found that several composite propellants were made more resistant to ignition, but that with high energy propellants, the continual resupply of air and reactant propellant materials overwhelms the contribution of additives and allows continued burning.
Aromatic amines such as diphenyl amine have been used to stabilize nitrate ester propellants. These amines are not compatible with nitramine explosives and could not be used with them as stabilizer.